Heterogeneity at the HLA-DRB1 allelic variation locus does not influence multiple sclerosis disease severity, brain...

Area of Science:

• Immunogenetics
• Neurology
• Clinical Research

Background:

• Human Leukocyte Antigen (HLA) class II alleles, particularly HLA-DRB1*1501 (DR15), are established risk factors for multiple sclerosis (MS).
• The impact of genetic heterogeneity within HLA-DRB1 alleles on the clinical progression and severity of MS remains incompletely understood and debated.
• This study investigates the influence of DR15 and other common DRB1 alleles on MS clinical outcomes in a large Australian population.

Purpose of the Study:

• To determine the association between common HLA-DRB1 alleles and genotypes and the clinical course of multiple sclerosis.
• To investigate the effect of HLA-DRB1 alleles on age of onset, disease severity, cognitive function, and brain atrophy in MS patients.
• To clarify the role of genetic heterogeneity in HLA-DRB1 on multiple sclerosis disease outcomes.

Main Methods:

• A cohort of 978 patients with relapsing-remitting MS and secondary progressive MS was analyzed for associations between HLA-DRB1 alleles/genotypes and clinical parameters.
• Disease severity was assessed using the Multiple Sclerosis Severity Score, progression index, and time to the second attack.
• Cognitive function was evaluated using the Symbol Digit Modalities Test (n=811), and brain atrophy was measured by the intercaudate ratio on MRI (n=745).

Main Results:

• Carriage of HLA-DRB1*1501 (DR15) was associated with a significantly earlier age of MS onset, with a reduction of 3.2 years in homozygotes and 1.3 years in heterozygotes.
• No significant association was found between the presence of DR15, DR1, DR3, or DR4 alleles (individually or in combination) and measures of clinical disease severity.
• HLA-DRB1 allele status did not influence cognitive performance or the degree of cerebral atrophy in the studied MS cohort.

Conclusions:

• This study confirms that HLA-DRB1 genetic heterogeneity does not significantly affect disease outcome in patients with relapsing forms of MS.
• The primary impact of HLA-DRB1 alleles on MS is related to the age of disease onset, particularly for HLA-DRB1*1501 (DR15) carriers.
• Further research may explore the mechanisms underlying the earlier onset associated with DR15 and its lack of influence on long-term disease progression.